kconfig/merge_config.sh: Support KCONFIG_CONFIG

All make targets support $KCONFIG_CONFIG because they
run scripts/kconf.  Make sure merge_config.sh accesses the
correct file in all cases.

Previously this script broke in two different code paths,
one for targets like kvmconfig (which use merge_config.sh -m
then call a target that respects KCONFIG_CONFIG) and one for
direct use of the script without -m, which called make rules
that edit KCONFIG_CONFIG but verified a different file.
Signed-off-by: Gabriel de Perthuis <g2p.code@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>

scripts/kconfig/merge_config.sh

@@ -32,7 +32,7 @@ usage() {
 	echo "  -m    only merge the fragments, do not execute the make command"
 	echo "  -n    use allnoconfig instead of alldefconfig"
 	echo "  -r    list redundant entries when merging fragments"
-	echo "  -O    dir to put generated output files"
+	echo "  -O    dir to put generated output files.  Consider setting \$KCONFIG_CONFIG instead."
 }
 
 RUNMAKE=true
@@ -82,6 +82,14 @@ if [ "$#" -lt 2 ] ; then
 	exit
 fi
 
+if [ -z "$KCONFIG_CONFIG" ]; then
+	if [ "$OUTPUT" != . ]; then
+		KCONFIG_CONFIG=$(readlink -m -- "$OUTPUT/.config")
+	else
+		KCONFIG_CONFIG=.config
+	fi
+fi
+
 INITFILE=$1
 shift;
 
@@ -124,9 +132,9 @@ for MERGE_FILE in $MERGE_LIST ; do
 done
 
 if [ "$RUNMAKE" = "false" ]; then
-	cp $TMP_FILE $OUTPUT/.config
+	cp -T -- "$TMP_FILE" "$KCONFIG_CONFIG"
 	echo "#"
-	echo "# merged configuration written to $OUTPUT/.config (needs make)"
+	echo "# merged configuration written to $KCONFIG_CONFIG (needs make)"
 	echo "#"
 	clean_up
 	exit
@@ -150,7 +158,7 @@ make KCONFIG_ALLCONFIG=$TMP_FILE $OUTPUT_ARG $ALLTARGET
 for CFG in $(sed -n "$SED_CONFIG_EXP" $TMP_FILE); do
 
 	REQUESTED_VAL=$(grep -w -e "$CFG" $TMP_FILE)
-	ACTUAL_VAL=$(grep -w -e "$CFG" $OUTPUT/.config)
+	ACTUAL_VAL=$(grep -w -e "$CFG" "$KCONFIG_CONFIG")
 	if [ "x$REQUESTED_VAL" != "x$ACTUAL_VAL" ] ; then
 		echo "Value requested for $CFG not in final .config"
 		echo "Requested value:  $REQUESTED_VAL"